Sry to add more to this after the changes were made but im re-watching the series and i noticed a few more things:
there is a picture in one of the ending themes where a female character has one breast exposed (not for sexual reasons per se, but ur not supposed to understand the image til R2) this is also in front of a Catholic-style alter with a stained glass angel behind it.
there is a scene where a boy is on top of a girl (because she attacked him and hes using self defense) but she is only covered by her jacket which she grabs as she attacks.
there is a shower seen featuring a boy, but it reveals nothing.
in other scenes, lady characters lay around topless, but face down.
the tight uniform thing also applies to men such as Suzaku's Knightmare piloting outfit.
a young girl is shown in a hospital bed with no clothing covering her torso, but thats because it was for a surgery or scan of some sort.
there is also large amounts of blood, while there is no gore, red blood does frequently go flying from off-sceen wounds.
Code Geass also grapples with the morality of war, the nature of human nature, racism, supposed atonement for sins, and when has lying gone too far. Mind control could be considered to a moral issue. the Britainian emperor deliberately quotes many of the Ten Commandments (in the sub and dub) as garbage in one of his speeches. A Christian-style funeral is held.
A nun is briefly scene (in a flashback whose nature is revealed in R2)
There were three different manga spin offs made. (Nightmare of Nunally, Lelouch of the Rebellion, and Suzaku of the Counterattack) as well as a series of light novels created, all available in english from bandai.
and in the story synopsis, Lelouch's illegimaticy has nothing to do with his desire to overthrow brittainia. he gave up his claim to the throne when the emperor (his father) cast off nunally because she was weak, cripples, and blind).
I think thats all I can think of.
Sry this wasnt in the earlier post. Sry.